Method and system for the transparent migration of virtual machines storage

Abstract

Method for transferring storage data of a virtual machine to be migrated from a first host device to a second host device via a communication network, including: running the virtual machine on the first host device; storing, on a local storage device of the first host device, a disk image used by the virtual machine; detecting, while the virtual machine is running on the first host device, any changes made to the disk image used by the virtual machine; establishing a connection over the communication network from the first host device to the second host device; transferring, to the second host device while the virtual machine is running on the first host device, the disk image used by the virtual machine and the detected any changes made; modifying the disk image transferred to the second host device in response to the detected any changes transferred to the second host device; and starting, using the modified disk image, a migrated virtual machine on the second host device at a current state of the virtual machine running on the first host device.

Description

REFERENCE TO RELATED APPLICATIONSThis application claims the benefit of European Patent Application No. 07 003 filed Feb. 21, 2007, which is hereby incorporated by reference herein.FIELDThe present invention relates in general to methods and systems for the transparent migration of virtual machine storage and in particular to a method and a system for transferring storage data of a virtual machine from a first host device to a second host device via a communication network.BACKGROUNDVirtualization is of growing importance in the world of IT deployments, in particular in the fields of data centers and wide-area server infrastructures.In the data centre virtualization allows the consolidation of services in such a way as to provide the control and protection facilities normally associated with dedicated separate hardware and software environments without higher costs. As an example it may be wise to separate the publicly visible web server of a company from the internal intranet serve...

AI Technical Summary

Problems solved by technology

One disadvantage of these is the higher cost of the extra hardware needed to provide for this.

They are also not suitable for situations where the performance or privacy available from local storage is necessary.

Additionally, they do not enable migration of virtual machines in the wide area, where shared storage is generally not available.

However, the I / O performance of such systems is far lower than that of local disks, thus making them unsuitable for a large number of applications and types of usage—for instance, for databases or storing swap files.

At the same time, the storage of virtual machine data on untrusted peers may be incompatible with the trust and privacy requirements of commercial services using the virtual machines.

Additionally, all above solutions require that custom file system software is installed and used by the migrated virtual machine, which introduces administration overhead.

This results in residual dependency problems: such systems are vulnerable to unpredictable source host unavailability, for instance in the case of a network disconnection or power failure.

At the same time, requiring the cooperation of source hosts conflicts with the federated, disconnected nature of platforms such as XenoServers, Grids, and PlanetLab, where servers are under the administrative control of different organizations and may be unpredictably shut down.

This makes this system unsuitable for migrating virtual machines that use large amounts of local storage.

Furthermore, this system does not perform live migration, i.e. the virtual machine has to be stopped at the source server while its data is being copied to the destination server.

For this reason, this system is unsuitable for the end-to-end, unmediated migration of virtual machines.

Furthermore, it does not support wide-area environments, where common storage access is not straightforward.

Thus, for file systems of a realistic size, this results in severe service interruption.

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